TicTacToe

tictactoe.java

import java.util.Scanner;

public class TicTacToe {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
       
        char[][] grid = new char[3][3];
       
        //initialize array
        for (int row = 0; row < grid.length; row++){
            for (int col = 0; col < grid[0].length; col++){
                grid[row][col] = ' ';
            }
        }
       
        int turn = 1;
        char player = 'X';
        boolean winner = false;
       
       
        //play a turn
        while (winner == false && turn <= 9){
            boolean validPlay;
            int column;
            int rowe;
            do {
                display(grid);
               
                System.out.print("Player " + player + ", choose a column: ");
                column = in.nextInt();
                
                System.out.print("Player " + player + ", choose a row: ");
                rowe = in.nextInt();
               
                //validate play
                validPlay = validate(column, rowe, grid);
               
            }while (validPlay == false);
           
            //drop the checker
            for (int row = 0; row <= grid.length; row++){
                if(grid[rowe][column] == ' '){
                    grid[rowe][column] = player;
                    break;
                }
            }
           
            //determine if there is a winner
            winner = isWinner(player,grid);
           
            //switch players
            if (player == 'X'){
                player = 'O';
            }else{
                player = 'X';
            }
           
            turn++;            
        } //end of turn
       
        display(grid);
        
        if (winner == true) {
            if (player == 'X') {
                System.out.println("O's won!");
            }
            else {
                System.out.println("X's won!");
            }
        }
        else {
            System.out.println("Tie game");
        }
    }
    
    public static void display(char[][] grid){
        System.out.println("  0 1 2");
        for (int row = 0; row < grid.length; row++){
        	if (row == 0)
        		System.out.print("0 ");
        	if (row == 1)
        		System.out.print("1 ");
        	if (row == 2)
        		System.out.print("2 ");
            for (int col = 0; col < grid[0].length; col++){
                System.out.print(grid[row][col]);
                if (col < 2) {
                	System.out.print("|");
                }
            }
            System.out.println();
            if (row < 2) {
            	System.out.println("  -+-+-");
            }
        }
        System.out.println();
    }
    
    public static boolean validate(int column, int rowe, char[][] grid){
        //valid column?
        if (column < 0 || column > grid[0].length){
            return false;
        }
        
        //valid row?
        if (rowe < 0 || rowe > grid[0].length){
            return false;
        }
       
        //full column / row?
        if (grid[rowe][column] != ' '){
            return false;
        }
       
        return true;
    }
    
    public static boolean isWinner(char player, char[][] grid){
        //check for 3 across
        for(int row = 0; row<grid.length; row++){
            for (int col = 0;col < grid[0].length - 2;col++){
                if (grid[row][col] == player   &&
                    grid[row][col+1] == player &&
                    grid[row][col+2] == player){
                   
                    return true;
                }
            }
        }
        
        //check for 3 up and down
        
        for (int row = 0; row < grid.length - 2; row++) {
            for (int col = 0; col < grid[0].length; col++) {
                if (grid[row][col] == player   &&
                    grid[row+1][col] == player &&
                    grid[row+2][col] == player) {
                    
                    return true;
                }
            }
        }
        
        //check diagonal
        
        for (int row = 2; row < grid.length; row++) {
            for (int col = 0; col < grid[0].length - 2; col++) {
                if (grid[row][col] == player   &&
                    grid[row - 1][col+1] == player &&
                    grid[row - 2][col+2] == player) {
                    
                    return true;
                }
            }
        }
        
        for (int row = 0; row < grid.length - 2; row++) {
            for (int col = 0; col < grid[0].length - 2; col++) {
                if (grid[row][col] == player   &&
                    grid[row + 1][col+1] == player &&
                    grid[row + 2][col+2] == player) {
                    
                    return true;
                }
            }
        }
        
        return false;
        
    }
}